Millions of people living along the Mekong River face a possibly irreversible depletion of key food supplies resulting from dam building and other diversions of its waters.

Deforestation upstream along the riverbanks and poor land and water use practices in Vietnam’s downstream Mekong Delta have added to what can only be called a looming crisis.

The Mekong is Southeast Asia’s longest river, with 60 to 70 million people depending on it for food, commerce, irrigation, transportation, and drinking water.

But the river’s slowly developing crisis rarely gains much attention from mainstream Western media.

This is partly because of a lack of transparency from regional governments and developers over plans by China, Laos, and Cambodia to build more dams. It’s not easy to obtain hard data on the dam projects.

And the Mekong River Commission (MRC), a regionally based international body which is supposed to help manage and contain threats to the river, has proven to be ineffective except when it comes to producing research reports.

The reports have been useful in raising awareness among experts and nongovernmental organizations focused on protecting the environment.

But the MRC has no authority to enforce its recommendations.

In late May, the Cambodia-based Phnom Penh Post reported that frustrated donors are turning away from the commission, with the MRC “losing more than half its funds and employees.”

The MRC is “becoming all but irrelevant,” the paper’s correspondent reported.

Impact in Laos and Cambodia

Just to the south of China’s Yunnan Province dams, Laos is already feeling the dams’ impact.

Laotian fishermen have been complaining for several years about lower water levels in the Mekong and a drop in their fish catch.

This is partly due to the loss of fish moving south that are blocked and ground up by the dams’ turbines. The dams also block adult fish trying to migrate upstream, and stop larvae and juveniles trying to swim downstream.

And dams trap sediment needed to enrich the soil in the riverbed and downstream lakes and tributaries.

When it comes to Laos, China’s example has not been helpful.

“China’s construction of hydropower projects on the upper Mekong River…has shown Laos that it can ignore protests from downstream countries about the negative effects of its dams,” says Brian Eyler, deputy director of the Southeast Asia program at the Stimson Center in Washington, D.C.

Eric Baran, a marine biologist based in Phnom Penh for the WorldFish Institute, estimates that some 60 percent of the population in Laos and Cambodia rely on fish for their entire daily protein consumption.

The Mekong dams in Laos could cut off natural migratory patterns of more than 110 fish species, Baran says.

In northeastern Cambodia, the Lower Sesan 2 dam, still under construction, has already reduced the fish catch of villagers in the area.

This has triggered widespread protests from villagers who are being displaced due to the inundation of villages upstream from the dam.

Thousands of people, many of them from ethnic minority groups, are expected to lose most of their fish resources because of the dam’s blocking of fish migrating from the Mekong and Sekong Rivers.

Ian Baird, an expert on the impact of dams in Southeast Asia at the University of Wisconsin, estimates that at least 78,000 people living above the Sesan 2 dam site will lose their access to migratory fish.

Baird told Radio Free Asia that on a broader scale “hundreds of thousands of people, or even millions, stand to be impacted in Cambodia and Vietnam as well as in Laos and Thailand, since fish migrations will be affected there.”

The role of Thailand is sometimes overlooked in the development of the Mekong River dams.

Chinese, Malaysian, and Thai companies are leading developers of the dams in Laos. And Thai banks finance some of the projects.

The Mekong Delta

In Vietnam’s Mekong Delta, a combination of drought, climate change, the effects of the El Nino phenomenon, and the impact of upstream Chinese dams is devastating rice crops.

The Delta, home to some 18 million people, is one of the world’s leading rice exporters.

A Vietnamese government “rice first” policy dating back to the mid-1970s that has encouraged farmers to grow three crops of rice per year has turned out to be counterproductive.

Farmers complain, meanwhile, that the dams have greatly reduced the amount of silt, or sediment, that once reached the Delta.

Silt helped to form the Mekong Delta over thousands of years. The loss of silt and rising sea levels have now resulted in salt water reaching nearly 40 miles into the Delta.

Some farmers have coped by raising shrimp in the briny water.

But a reduction in rice exports now means a drop of income for many.

What's next for the Mekong?

On a more positive note, Richard Cronin and Courtney Weatherby argued in a Stimson Center report in October last year that a combination of factors could lead to less dam building.

These factors would include “rising political and financial risks and changing global energy prices” as well as a “new interest from donor governments and institutions in identifying alternatives to destructive mainstream dams…”

“The possibility that not all of the planned dams may go forward,” the authors of the report say, “opens up a new opportunity for Laos to reconsider its current commitment to all nine of its planned Mekong dams.”

The Lao government wants to use its hydropower for electric power exports to other countries, such as neighboring Thailand. Its aim is to become the “battery of Southeast Asia.”

But a preliminary study by the Asian Development Bank (ADB) found that if Laos can upgrade older dams on tributaries of the Mekong and link them with a national grid, this will give Laos the short-term revenues it seeks without further disrupting the river.

“Another China-related factor that may be critical to the viability of dams on the mainstream and major tributaries is the question of future water availability,” says the Stimson report.

The Mekong has its origins in Tibet. “As climate change melts Himalayan glaciers and changes patterns, scientists are questioning the long-term utility of dams that depend on regular flows to operate during the dry season,” the report says.

“Should increasingly water-stressed China prioritize other uses of water in the Upper Mekong over electricity production," the report adds, "the planned mainstream dams in the Lower Mekong might not receive enough water to operate during the driest three or four months of the year."

This is when flows from China are the region's most important source of water, the report says.